REGULATORY GUIDE

U.S. NUCLEAR REGULATORY COMMISSION
July 2013
Revision 3
REGULATORY GUIDE
OFFICE OF NUCLEAR REGULATORY RESEARCH
REGULATORY GUIDE 1.130
SERVICE LIMITS AND LOADING COMBINATIONS FOR
CLASS 1 PLATE-AND-SHELL-TYPE SUPPORTS
A. INTRODUCTION
Purpose
This regulatory guide delineates levels of service limits and appropriate combinations of loadings
associated with normal operation, postulated accidents, and specified seismic events for the design of
Class 1 plate-and-shell-type component and piping supports, as defined in Subsection NF of the American
Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, “Rules for
Construction of Nuclear Power Plant Components” (Ref. 1), that the staff of the U.S. Nuclear Regulatory
Commission (NRC) considers acceptable. This guide applies to light-water-cooled reactors.
Applicable Rules and Regulations
General Design Criterion 2, “Design Bases for Protection Against Natural Phenomena,” of
Appendix A, “General Design Criteria for Nuclear Power Plants,” to Title 10, Part 50, “Domestic
Licensing of Production and Utilization Facilities,” of the Code of Federal Regulations (10 CFR) (Ref. 2)
requires that the design bases for structures, systems, and components important to safety reflect
appropriate combinations of the effects of normal and accident conditions with the effects of natural
phenomena such as earthquakes. The failure of members designed to support safety-related components
and piping could jeopardize the ability of the supported component or piping to perform its safety
function. This is also applicable under 10 CFR Part 52, “Licenses, Certifications, and Approvals for
Nuclear Power Plants” (Reg. 3)
Purpose of Regulatory Guides
The NRC issues regulatory guides to describe to the public methods that the staff considers
acceptable for use in implementing specific parts of the agency’s regulations, to explain techniques that
the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to
applicants. Regulatory guides are not substitutes for regulations and compliance with them is not
Written suggestions regarding this guide or development of new guides may be submitted through the NRC’s public Web site under the
Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.html.
Electronic copies of this regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRC’s
public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/. The
regulatory guide is also available through the NRC’s Agencywide Documents Access and Management System (ADAMS) at
http://www.nrc.gov/reading-rm/adams.html, under ADAMS Accession No. ML13141A667.
required. Methods and solutions that differ from those set forth in regulatory guides will be deemed
acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or
license by the Commission.
Information Collection Requirements
This regulatory guide contains information collections that are covered by the requirements of
10 CFR Part 50 and 10 CFR Part 52 that the Office of Management and Budget (OMB) approved under
OMB control number 3150-0011 and 3150-0151. The NRC may neither conduct nor sponsor, and a
person is not required to respond to, an information collection request or requirement unless the
requesting document displays a currently valid OMB control number.
B. DISCUSSION
Reason for Revision
Revision 3 of RG 1.130 updates the NRC’s approval of the ASME Boiler and Pressure Vessel
Code (ASME B&PV Code), Section III, Division 1, 2007 Edition through the 2008 Addenda, as one
acceptable means for delineating levels of service limits and appropriate combinations of loadings
associated with normal operation, postulated accidents, and specified seismic events for the design of
Class 1 plate-and-shell-type component and piping supports. Revision 2 of RG 1.130 approved the 2001
Edition through the 2003 Addenda of the ASME B&PV Code. None of the changes from the 2001
Edition through the 2003 Addenda, to the 2007 Edition through the 2008 Addenda, were in the areas
covered by RG 1.130. In addition, Revision 3 of RG 1.130 includes editorial changes to improve clarity
and provide a new standardized format for regulatory guides.
Background
Load-bearing members classified as component and piping supports are essential to the safety of
nuclear power plants because they hold components and piping in place during loadings associated with
normal and upset plant conditions under the stress of specified seismic events, thereby permitting system
components and piping to function properly. Load-bearing members also prevent excessive movement of
components and piping during the loadings associated with emergency and faulted plant conditions
combined with a specified seismic event or other natural phenomena, thereby helping to mitigate system
damage. Component and piping supports are deformation-sensitive because large deformations can
significantly change the stress distribution in the support system and its supported components and
piping.
To provide a consistent level of safety, the ASME Code classification for component and piping
supports should, as a minimum, be the same as that of the supported components and piping. This guide
delineates levels of service limits and loading combinations, as well as supplementary criteria, for Class 1
plate-and-shell-type component and piping supports, as defined by NF-1212 of Section III of the ASME
Code. This guide does not address snubbers.
Subsection NF of Section III permits the use of three methods for the design of Class 1 plate-andshell-type component and piping supports: (1) linear elastic analysis, (2) load rating, and
(3) experimental stress analysis. For each method, the ASME Code delineates allowable stress or loading
limits for various ASME Code service levels, as defined by NF-3113 and NCA-2142.4(b) of Section III,
so that these limits can be used in conjunction with the resultant loadings or stresses from the appropriate
plant conditions. Because the ASME Code does not specify loading combinations, guidance is needed to
provide a consistent basis for the design of supports.
Rev. 3 of RG 1.130, Page 2
Component and piping supports considered in this guide are located within seismic Category I
structures and, therefore, are assumed to be protected against loadings from natural phenomena (or
manmade hazards) other than the specified seismic events. Thus, only the specified seismic events need
to be considered in combination with the loadings associated with plant conditions to develop appropriate
loading combinations. Loadings caused by any natural phenomena other than seismic events should be
considered on a case-by-case basis.
1.
Design by Linear Elastic Analysis
Tables 2A, 2B, 4, U, and Y-1 in Subpart 1 of Part D of Section II and Tables 1, 3, 4, and 5 of the
latest accepted versions1 of ASME Code Cases N-71, “Additional Materials for Subsection NF,
Class 1,2,3, and MC Component supports Fabricated by Welding, Section III, Division 1,” and N-249,
“Additional Materials for Subsection NF, Class 1,2,3, and MC Component Supports Fabricated without
Welding, Section III, Division 1,” provide the material properties when the linear elastic analysis method
is used to design Class 1 plate-and-shell-type component and piping supports. These tables list values at
various temperatures for the design stress intensity Sm, the minimum yield strength Sy, and the ultimate
tensile strength Su.
NF-3522 and NF-3622 limit the primary stress for service levels A, B, and C to less than or equal
to one-half the critical buckling strength of the component or piping support at temperature. Guidance in
F-1331.5(a) limits the increase for service level D to two-thirds of the critical buckling strength of the
component or piping support at temperature. Because buckling prevents “shakedown” in a load-bearing
member, it must be regarded as controlling for the level A through level D service limits. Also, buckling
is the result of the interaction of the geometry of the load-bearing member and its material properties
(i.e., elastic modulus E and minimum yield strength Sy). Because both of these material properties change
with temperature, calculation of the critical buckling stresses should use the values of E and Sy of the
support material at temperature.
Allowable service limits for bolted connections are derived on a different basis, which varies with
the size of the bolt. For this reason, the increases permitted by NF-3221.2 and F-1332 of Section III do
not directly apply to bolts and bolted connections. For bolts, allowable increases for service levels B,
C and D are specified in NF-3225.
2.
Design by Load Rating
NF-3280 specifies load ratings for service level A, B, and C limits. F-1332.7 specifies the load
rating for the service level D limit.
3.
Design by Experimental Stress Analysis
Although II-1430 in Appendix II to Section III defines the test collapse load for the experimental
stress analysis method, it does not delineate the method’s design limits or various operating condition
categories. The interim method described in this guide remedies this deficiency.
1
Regulatory Guide 1.84, “Design, Fabrication, and Materials Code Case Acceptability, ASME Section III,” provides
guidance for the acceptability of ASME Section III Code Cases and their revisions, including Code Cases N-71 and
N-249. Code Cases identified as “Conditionally Acceptable Section III Code Cases” are acceptable, provided that they
are used with the identified limitations or modifications.
Rev. 3 of RG 1.130, Page 3
4.
Large Deformations
The design of component and piping supports is an integral part of the design of a system and its
components and piping. A complete and consistent design is possible only when the interaction between
the system, component, piping, and support is properly considered. When all four elements are evaluated
on an elastic basis, the interaction is usually valid because individual deformations are small. However, if
the design process uses plastic analysis methods, large deformations may occur that would result in
substantially different stress distributions.
For the evaluation of level D service limits, Appendix F to Section III permits the use of plastic
analysis methods in certain acceptable combinations for all four elements. The selection of these
acceptable combinations assumes that component and piping supports are more deformation-sensitive
(i.e., their deformation in general will have a large effect on the stress distribution in the system and its
components and piping).
Because large deformations always affect stress distribution, care should be exercised even when
using the plastic analysis method in the methodology combination approved in Appendix F. This is
especially important for identifying buckling or instability problems when the change of geometry should
be considered to avoid erroneous results.
5.
Function of Supported System
In selecting the level of service limits for different loading combinations, the designer should take
into account the function of the supported system. To ensure that systems whose normal function is to
prevent or mitigate the consequences of events associated with an emergency or faulted plant condition
(e.g., the function of the emergency core cooling system during faulted plant conditions) will operate
properly regardless of plant condition, the use of ASME Code Section III level A or B service limits of
Subsection NF (or other justifiable limits provided by the Code) is appropriate.
6.
Deformation Limits
Because component and piping supports are deformation-sensitive load-bearing elements,
satisfying the service limits of Section III will not automatically ensure their proper function. If stated in
the ASME Code design specification, deformation limits may be the controlling criterion. By contrast, if
a particular plant condition does not require the function of a component or piping support, the stresses or
loads resulting from the loading combinations under the particular plant condition do not need to satisfy
the design limits for the plant condition.
7.
Definitions
Critical buckling strength. The strength at which lateral displacements start to develop simultaneously
with in-plane or axial deformations.
Design condition. The loading condition defined by NF-3112 of Section III of the ASME Boiler and
Pressure Vessel Code.
Emergency plant conditions. Those operating conditions that have a low probability of occurrence.
Faulted plant conditions. Those operating conditions associated with postulated events of extremely low
probability.
Rev. 3 of RG 1.130, Page 4
Levels of service limits. Four levels of service limits—A, B, C, and D—defined by Section III of the
ASME Boiler and Pressure Vessel Code for the design of loadings associated with different plant
conditions for components and piping and component and piping supports in nuclear power
plants.
Normal plant conditions. Those operating conditions that occur in the course of system startup,
operation, hot standby, refueling, and shutdown, with the exception of upset, emergency, or
faulted plant conditions.
Operating-basis earthquake. Seismic event defined in Appendix A, “Seismic and Geologic Siting
Criteria for Nuclear Power Plants,” to 10 CFR Part 100, “Reactor Site Criteria.”
Operating condition categories. Categories of design limits for component and piping supports defined
by NF-3113 of Section III of the ASME Code.
Plant conditions. Operating conditions of the plant categorized as normal, upset, emergency, and faulted
plant conditions.
Safe-shutdown earthquake. Seismic event defined in Appendix A to 10 CFR Part 100.
Service limits. Stress limits for the design of component and piping supports, defined by Subsection NF
of Section III of the ASME Boiler and Pressure Vessel Code.
Specified seismic events. Operating-basis earthquake and safe-shutdown earthquake, defined above.
System mechanical loadings. The static and dynamic loadings developed by the system operating
parameters—including deadweight, pressure, and other external loadings—and effects resulting
from constraints of free-end movements, but excluding effects resulting from thermal and peak
stresses generated within the component support.
Ultimate tensile strength. Material property based on the engineering stress-strain relationship.
Upset plant conditions. Those deviations from the normal plant condition that have a high probability of
occurrence.
Harmonization with International Standards
ASME is the leading international developer of codes and standards associated with the art,
science, and practice of mechanical engineering. Since the first issuance in 1914 of the Boiler & Pressure
Vessel Code, ASME has maintained a commitment to enhance public safety and technological
advancement. Pertinent to this regulatory guide, Subsection NF of the ASME Boiler and Pressure Vessel
Code, Section III, “Rules for Construction of Nuclear Power Plant Components,” contains requirements
for the material, design, fabrication, and examination of supports which are intended to conform to the
requirements for Classes 1,2,3 and MC construction. This regulatory guide incorporates similar design
and preoperational testing guidelines and it is consistent with the basics safety principles provided in
Subsection NF of Section III of the BPVC.
Documents Discussed in Staff Regulatory Guidance
This regulatory guide endorses the use of one or more codes or standards developed by external
organizations, and other third party guidance documents. These codes, standards and third party guidance
Rev. 3 of RG 1.130, Page 5
documents may contain references to other codes, standards or third party guidance documents
(“secondary references”). If a secondary reference has itself been incorporated by reference into NRC
regulations as a requirement, then licensees and applicants must comply with that standard as set forth in
the regulation. If the secondary reference has been endorsed in a regulatory guide as an acceptable
approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC
staff for meeting that regulatory requirement as described in the specific regulatory guide. If the
secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a
regulatory guide, then the secondary reference is neither a legally binding requirement nor a “generic”
NRC approval as an acceptable approach for meeting an NRC requirement. However, licensees and
applicants may consider and use the information in the secondary reference, if appropriately justified and
consistent with current regulatory practice, consistent with applicable NRC requirements such as
10 CFR 50.59, “Changes, Tests, and Experiments.”
C. STAFF REGULATORY GUIDANCE
The construction of ASME Code2 Class 1 plate-and-shell-type component and piping supports—
except snubbers, which this guide does not address—should follow the rules of Subsection NF of Section
III of the Code, as supplemented by the following stipulations:3
1.
The classification of component and piping supports should, as a minimum, be the same as that of
the supported components and piping.
2.
The critical buckling strength should always constrain the service limits for component and
piping supports designed by linear elastic analysis. The calculation of critical buckling strength
should use materials at temperature properties. Critical buckling stresses for service level A,
B, C, and D limits should be maintained in accordance with paragraphs NF-3522, NF-3622 and
F-1332.5 of Section III for loadings combined according to Regulatory Position 3 of this guide.
Service limits related to critical buckling strength should not increase unless the ASME Code
specifically allows such an increase. Service limits related to critical buckling strength should not
increase unless the ASME Code specifically allows such an increase.
3.
For component and piping supports subjected to the combined loadings of (1) the vibratory
motion of the operating-basis earthquake and (2) system mechanical loadings4 associated with
either the ASME Code design condition or normal or upset plant conditions, the design approach
should be as follows:5,6
2
ASME Boiler and Pressure Vessel Code, Section III, Division I, 2007 Edition through the 2008 Addenda.
3
If the function of a component or piping support is not required during a plant condition, satisfaction of the design
limits of the support for that plant condition is not needed, provided excessive deflections or failure of the support will
not result in the loss of function of any other safety-related system.
4
System mechanical loadings include all non-self-limiting loadings and the effects resulting from constraints of free-end
displacements, but not the effects resulting from thermal or peak stresses generated within the component or piping
support.
5
Because component and piping supports are deformation-sensitive in the performance of their service requirements,
satisfying these limits does not ensure the fulfillment of their functional requirements. Any deformation limits
specified by the design specification may be controlling and should be satisfied.
6
Because the design of component and piping supports is an integral part of the design of the system and the component
and piping, the designer should ensure that methods used for the analysis of the system, component and piping, and
support are compatible. The designer of component and piping supports should consider large deformations in the
system or components and piping.
Rev. 3 of RG 1.130, Page 6
4.
5.
6.
a.
Supports designed by using the linear elastic analysis method should not exceed (1) the
service limits of paragraphs NF-3522 and NF-3622 for design loadings and level A and B
service limits and (2) the constraints discussed in Regulatory Position 2 of this guide.
b.
Supports designed by the load-rating method should not exceed the load rating for
level A or level B limits of NF-3280 of Section III.
c.
Supports designed by the experimental stress analysis method should not exceed the test
collapse load determined by II-1430 of Section III divided by 1.7.
The design of component and piping supports subjected to the system mechanical loadings5
associated with the emergency plant condition should adhere to the following design limits,
except when the normal function of the supported system is to prevent or mitigate the
consequences of events associated with the emergency plant condition (in which case, Regulatory
Position 6 then applies):6,
a.
Supports designed by the linear elastic analysis method should not exceed the service
limits of NF-3522 and NF-3622 of Section III and Regulatory Position 2.
b.
Supports designed by the load-rating method should not exceed the load rating for level C
limits of NF-3280 of Section III.
c.
Supports designed by the experimental stress analysis method should not exceed the test
collapse load determined by II-1430 of Section III and divided by 1.3.
The design of component and piping supports subjected to the combined loadings of (1) the
vibratory motion of the safe-shutdown earthquake, (2) the system mechanical loadings5
associated with the normal plant condition, and (3) the dynamic system loadings associated with
the faulted plant condition should adhere to the following design limits, except when the normal
function of the supported system is to prevent or mitigate the consequences of events associated
with the faulted plant condition (in which case, Regulatory Position 6 then applies):6
a.
Supports designed by the linear elastic analysis method should not exceed the service
limits of F-1332 of Section III.
b.
Supports designed by the load-rating method should not exceed the value of
TL × 0.7 Su/Su*, where TL and Su* are defined according to F-1332.7 of Section III
and Su is the ultimate tensile strength of the material at service temperature.
c.
Supports designed by the experimental stress analysis method should not exceed the test
collapse load determined by II-1430.
d.
If plastic methods are used for the design of supports, the combined loadings of
Regulatory Position 5 should include loads such as constraints of free-end displacements.
The design should not exceed the service limits of F-1340 of Section III.
The design of component and piping supports in systems for which the normal function is to
prevent or mitigate the consequences of events associated with an emergency or faulted plant
condition should adhere to the limits described in Regulatory Position 3 or other justifiable limits
such as the level C or level D service limits provided by the ASME Code. The design
specification should define these limits so that the function of the supported system will be
Rev. 3 of RG 1.130, Page 7
maintained when the supports are subjected to the loading combinations described in Regulatory
Positions 4 and 5.
D. IMPLEMENTATION
The purpose of this section is to provide information on how applicants and licensees7 may use
this guide and to provide information regarding the NRC’s plans for using this regulatory guide. In
addition, it describes how the NRC staff complies with 10 CFR 50.109, “Backfitting” and any applicable
finality provisions in 10 CFR Part 52, “Licenses, Certifications, and Approvals for Nuclear Power
Plants.”
Use by Applicants and Licensees
Applicants and licensees may voluntarily 8 use the guidance in this document to demonstrate
compliance with the underlying NRC regulations. Methods or solutions that differ from those described
in this regulatory guide may be deemed acceptable if they provide sufficient basis and information for the
NRC staff to verify that the proposed alternative demonstrates compliance with the appropriate NRC
regulations. Current licensees may continue to use guidance the NRC found acceptable for complying
with the identified regulations as long as their current licensing basis remains unchanged.
Licensees may use the information in this regulatory guide for actions that do not require NRC
review and approval such as changes to a facility design under 10 CFR 50.59, “Changes, Tests, and
Experiments.” Licensees may use the information in this regulatory guide or applicable parts to resolve
regulatory or inspection issues.
Use by NRC Staff
The NRC staff does not intend or approve any imposition or backfitting of the guidance in this
regulatory guide. The NRC staff does not expect any existing licensee to use or commit to using the
guidance in this regulatory guide, unless the licensee makes a change to its licensing basis. The NRC
staff does not expect or plan to request licensees to voluntarily adopt this regulatory guide to resolve a
generic regulatory issue. The NRC staff does not expect or plan to initiate NRC regulatory action that
would require the use of this regulatory guide. Examples of such unplanned NRC regulatory actions
include issuance of an order requiring the use of the regulatory guide, requests for information under
10 CFR 50.54(f) as to whether a licensee intends to commit to use of this regulatory guide, generic
communication, or promulgation of a rule requiring the use of this regulatory guide without further
backfit consideration.
During regulatory discussions on plant specific operational issues, the staff may discuss with
licensees various actions consistent with staff positions in this regulatory guide, as one acceptable means
of meeting the underlying NRC regulatory requirement. Such discussions would not ordinarily be
considered backfitting even if prior versions of this regulatory guide are part of the licensing basis of the
facility. However, unless this regulatory guide is part of the licensing basis for a facility, the staff may
not represent to the licensee that the licensee’s failure to comply with the positions in this regulatory
guide constitutes a violation.
7
In this section, “licensees” refers to licensees of nuclear power plants under 10 CFR Parts 50 and 52; the term
“applicants” refers to applicants for licenses and permits for (or relating to) nuclear power plants under 10 CFR Parts
50 and 52 and applicants for standard design approvals and standard design certifications under 10 CFR Part 52.
8
In this section, “voluntary” and “voluntarily” mean that the licensee is seeking the action of its own accord, without the
force of a legally binding requirement or an NRC representation of further licensing or enforcement action.
Rev. 3 of RG 1.130, Page 8
If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC staff’s
consideration of the request involves a regulatory issue directly relevant to this new or revised regulatory
guide and (2) the specific subject matter of this regulatory guide is an essential consideration in the staff’s
determination of the acceptability of the licensee’s request, then the staff may request that the licensee
either follow the guidance in this regulatory guide or provide an equivalent alternative process that
demonstrates compliance with the underlying NRC regulatory requirements. This is not considered
backfitting as defined in 10 CFR 50.109(a)(1) or a violation of any of the issue finality provisions in 10
CFR Part 52.
Additionally, an existing applicant may be required to comply to new rules, orders, or guidance if
10 CFR 50.109(a)(3) applies.
If a licensee believes that the NRC is either using this regulatory guide or requesting or requiring
the licensee to implement the methods or processes in this regulatory guide in a manner inconsistent with
the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in
accordance with the guidance in NUREG-1409, “Backfitting Guidelines,” (Ref. 4) and NRC Management
Directive 8.4, “Management of Facility-Specific Backfitting and Information Collection” (Ref. 5).
Rev. 3 of RG 1.130, Page 9
REFERENCES9
1.
American Society of Mechanical Engineers (ASME), Section III, “Rules for Construction of
Nuclear Power Plant Components,” ASME Boiler and Pressure Vessel Code, American Society
of Mechanical Engineers, New York, NY.10
2.
U.S. Code of Federal Regulations (CFR), Title 10, Energy, Part 50, “Domestic Licensing of
Production and Utilization Facilities.”
3.
U.S. Code of Federal Regulations (CFR), Title 10, Energy, Part 52, “Licenses, Certifications, and
Approvals for Nuclear Power Plants.”
4.
U.S. Nuclear Regulatory Commission (NRC), NUREG-1409, “Backfitting Guidelines,” NRC,
Washington, DC.
5.
NRC, Management Directive 8.4, “Management of Facility-specific Backfitting and Information
Collection,” NRC, Washington, DC.
9
Publicly available NRC published documents are available electronically through the NRC Library on the NRC’s public Web site at:
http://www.nrc.gov/reading-rm/doc-collections/. The documents can also be viewed on-line or printed for a fee in the NRC’s Public
Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555;
telephone 301-415-4737 or 800-397-4209; fax 301-415-3548; and e-mail [email protected].
10
Copies of American Society of Mechanical Engineers (ASME) standards may be purchased from ASME, Two Park Avenue, New
York, NY 10016-5990; Telephone 800-843-2763. Purchase information is available through the ASME Web site store at
http://www.asme.org/Codes/Publications/.
Rev. 3 of RG 1.130, Page 10